Fuel rail assemblies for gasoline engines often comprise a metal fuel rail that contains the fuel injectors. Certain advantages may accrue by using a molded plastic part for the fuel rail. For example, a molded plastic fuel rail designed to accept bottom-feed fuel injectors can save on weight and provide for a reduction in the envelope that is occupied by the fuel rail assembly, and these are important considerations for automotive vehicle manufacturers. Furthermore, a single plastic fuel rail may provide certain savings over a metal fuel rail when the metal fuel rail is an assembly of individual metal pieces which must be joined in a fluid-tight manner by suitable joining processes.
Since a molded plastic fuel rail is essentially a tubular part, the mold for fabricating it typically comprises one or more core pins that must be extracted from the interior of the plastic after the plastic has solidified in the mold. In a mold in which a single core pin forms the main fuel rail hole the core pin is extracted by withdrawing it from one axial end of the fuel rail. Due to part and molding considerations the main fuel rail hole at this end of the fuel rail will typically be larger than the diameter of a metal fuel tube that is intended to be inserted into it to form a joint between the fuel tube and the fuel rail. The problem is therefore posed as to how to create such a joint in a manner that will be economical for production purposes, yet will also comply with relevant engineering specifications. The present invention is directed to a solution to this problem.
Briefly, the solution is embodied by means of a tubular plug that fits in a sealed manner to the end of the main fuel rail hole and that itself receives the fuel tube in a sealed manner. A slot extends through the sidewall of the fuel rail to intersect the main fuel rail hole closely adjacent the end of the fuel rail. A tube retainer clip passes through the slot and comprises a U-shaped notch that allows the clip to slide over the metal fuel tube. The fuel tube has a circular exterior bead that is overlapped by the margin of the clip that borders the U-shaped notch such that the bead is disposed more interiorly of the fuel rail hole with the result that the metal fuel tube is captured and cannot be withdrawn from the main fuel rail hole unless the clip is first removed. Yet, the tube can still be rotated within the fuel rail while captured, and this attribute is useful in allowing for proper alignment when the fuel rail assembly is being installed on an engine. In the completed fuel rail assembly, the clip is itself retained in its fuel-tube-capturing position by a suitable retention means. In one embodiment this retention means is by an integral clasp portion of the clip which snaps onto the fuel tube just beyond the end of the main fuel rail hole. In another embodiment this retention means comprises an apertured tab that is integrally formed with the clip, and a threaded fastener that passes through the aperture in the tab and into a threaded hole in a boss on the fuel rail. When a fuel injector retainer is assembled onto the fuel rail for the purpose of retaining the injectors in their sockets in the rail, the installed tube retainer clip may be prevented from being removed by a portion of the fuel injector retainer being disposed in an interference relationship to the clip.
Principles of the invention can also be applied to join another fuel tube to the opposite end of the main fuel rail hole whenever the fuel rail has a complete through-hole for its main fuel hole. Typically a majority of the length of such a through-hole is created by a molding core pin which is extracted from one end of the solidified plastic, and the opposite open end of the fuel rail which is to receive the other fuel tube may be made sufficiently small that the use of a plug is unnecessary, in which case, the other fuel tube will fit in a sealed manner directly into the opposite end of the through-hole without such an intervening plug.
Further features, advantages and benefits of the invention, along with those already introduced, will be seen in the ensuing description and claims which should be considered along with the accompanying drawings. The drawings, in which like reference numerals designate like parts, disclose a preferred embodiment of the invention according to the best mode contemplated at the present time in carrying out the invention.